1. Field of the Invention
The invention relates to a device for obtaining a permeate from a concentrate, in particular, raw water comprised of a separating chamber which is divided by a filter membrane into a concentrate chamber and a permeate chamber with an inlet line opening into the concentrate chamber for the concentrate and a concentrate line branched off the concentrate chamber as well as a permeate line branching off the permeate chamber, to which is connected an accumulator which is divided by a non-permeable separating membrane into a storage chamber and a pressurized chamber, wherein the storage chamber is connected to the permeate line and the pressurized chamber is connected via a control valve to the concentrate line.
2. Description of the Related Art
Especially in areas close to the ocean, the raw water provided to households has a high salt content based on which all needs in regard to the use of the raw water cannot be satisfied. The thus required treatment of the raw water is carried out in devices which have a separating chamber with a membrane module which by means of a separation method such as, for example, reverse osmosis divides the raw water into a concentrated solution (concentrate) and a desalinated solution (permeate). The salt molecules of the raw water in this case cannot overcome the osmotic membrane even under pressure and remain thus in the concentrate. Accordingly, the permeate filtered through the membrane remains substantially free of salt molecules.
From DE 39 14 940 A1 a device of the aforementioned kind for treatment of raw water is known. By means of switchable valves permeate is obtained when removing raw water which, with displacement of filling water, flows into an accumulator. For the removal of permeate, several valves must be switched which is technically complex and cumbersome. In this connection, the raw water line is connected with the filling water volume so that the permeate flows out of the accumulator substantially under the line pressure. The permeate is generated in the low-pressure range which results in only a minimal permeate yield.
Reverse osmosis in the low-pressure range is also used in the device according to DE 195 45 277 A1 which has the consequence that the permeate yield is low in comparison to the concentrate. As demonstrated in practice, in the low-pressure range 5-20% of the supplied raw water is obtained as permeate. This permeate flows into a permeate storage device which must be designed such that it can also cover a discontinuous increased permeate demand. The minimal permeate yield results in that the concentrate differs with regard to quality only minimally from the raw water and can thus be used for many applications in the household such as washing dishes and cleaning without reservations. As a result of the minimal permeate yield in the low-pressure range a large amount of raw water is required which usually flows out as waste water without having been used.
From Japanese laid open patent JP-62-91204 it is known to arrange an outflow vessel at the filter outlet for enhancement of the filter output whose airspace above the liquid level is loaded by under pressure by means of a jet pump. The jet pump is arranged within the concentrate circuit which is also operated by a pump.
It is an object of the invention to further develop a device of the aforementioned kind such that the production and making available of permeate, for example, as drinking water, is possible with minimal energy consumption and raw water use.
The object is solved according to the invention in that the concentrate line opens into the jet head of a jet nozzle whose accelerated exit jet enters into an outlet concentrate line positioned at a distance opposite thereto, and in that a suction line is branched off an under pressure chamber of the jet nozzle surrounding the exit jet and is connected with the pressurized chamber.
The selection of an accumulator whose pressurized chamber is connected with the concentrate line by a jet nozzle combines storage and conveyance of the permeate in the permeate network within a single device. In this connection, the under pressure or over pressure in the pressurized chamber is derived solely from the water supply network. The alternating switching between generation of an under pressure or an over pressure is realized by the user when selecting concentrate consumption or permeate consumption.
When concentrate is being consumed, the concentrate flows from the concentrate chamber of a separating chamber and reaches via a concentrate line a jet head of the jet nozzle. The accelerated exit jet generates upon entering a line positioned opposite the jet head at a spacing thereto a pressure drop in its immediate vicinity. The coupling of the under pressure chamber of the jet nozzle comprising the exit jet to the pressurized chamber of the accumulator makes it possible to employ this pressure drop as a suction effect. Upon simultaneous outflow of the concentrate, the pressurized chamber of the accumulator which is coupled with the jet nozzle and is filled correspondingly with the concentrate, is emptied by suction. Since the pressure membrane of the accumulator yields to the pressure, the suction effect is transmitted onto the oppositely positioned chamber which is connected via the permeate line with the permeate chamber of the separating chamber and thus increases the pressure gradient via the membrane and thus also the permeate yield. The emptying of the pressurized chamber of the accumulator filled with concentrate is coupled with the filling of the oppositely positioned storage chamber with the permeate. Solely by the pressure which is present within the water supply network of the water supply line, the under pressure in the accumulator is achieved without additional pump devices.
The connection of the permeate chamber of the separating chamber with the accumulator makes an increase of the permeate yield possible. When an under pressure is present in the accumulator, the permeate is sucked in from the permeate chamber of the separating chamber. The under pressure in the accumulator is distributed within the permeate chamber and increases the efficiency of the separating membrane in the separating chamber. The concentrate can further be used as general use water because the separation is carried out in the low-pressure range. The concentrate differs slightly from the raw water and can therefore be used without problems for flushing processes in the household. During consumption of concentrate or raw water, the permeate is produced and collected in the accumulator. When the permeate is used in the household, the user switches the mixed water faucet to the permeate line. The accumulator in emptied from the permeate contained in the storage chamber, additionally enhanced by the static over pressure of the concentrate, which is built up within the accumulator via the concentrate line connected to the jet nozzle.
According to a further development of the invention, an additional separating chamber is connected to the concentrate line downstream of the jet nozzle. Its corresponding permeate chamber is connected with the storage chamber of the accumulator. Operating this additional separating chamber is realized by means of controlling an inlet valve which is mounted in the concentrate line for supplying the separating chamber. The control is connected with a switching contact connected with the pressurized chamber which controls opening of the inlet valve as a function of the filling amount in the storage chamber. For this purpose, a magnet is mounted on the pressure membrane at the side of the storage chamber via which a switching contact can be actuated in a contactless way for switching the inlet valve when an increased permeate demand is present.